This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The polycystic ovarian syndrome (PCOS) is a common disorder marked by irregular ovulation and hyperandrogenism. Hyperandrogenemia during adolescence can be a forerunner of adult PCOS. However, the progression of hormonal abnormalities leading to PCOS are unclear. We will examine hormonal profiles (e.g., LH, FSH, progesterone, testosterone, estradiol) during pubertal maturation in adolescent girls with and without elevated plasma androgens. The working hypothesis is that, in pubertal girls without hyperandrogenemia, overnight rises of P are associated with a reduction of LH frequency during the waking morning hours. However, in pubertal girls with hyperandrogenemia, LH frequency will be higher than normal during both the day and night, despite similar or higher P levels. The studies will involve frequent blood sampling over 18 hours. We will assess differences in hormone parameters between time blocks (1900-2300 h, 2300-0300 h, 0300-0700 h, 0700-1100 h) in individuals to evaluate diurnal changes. We will compare such changes between those with hyperandrogenemia and those without hyperandrogenemia.